1. Field of the Invention
The present invention relates to illumination apparatuses, and more particularly, to an illumination apparatus employing LED (Light Emitting Diode).
2. Description of Related Art
The lighting apparatus attached to a bicycle must ensure favorable field of view in the frontward direction while suppressing excessive glare with respect to vehicles coming from the opposite direction. A conventional illumination apparatus is implemented as set forth below.
(a) The light emitted from the filament arranged in the proximity of the focal point of the parabolic mirror diverges in all directions. All the light other than the light emitted directly frontward is reflected at the parabolic mirror to form frontward parallel light rays. These light rays are set to form a predetermined light distribution by the front lens together with the light directly output frontward (for example, refer to Japanese Patent Laying-Open Nos. 2002-50212 and 2002-50213).
(b) The light emitted from the filament is set to form a desired light distribution by a multi-surface mirror to be output in the frontward direction. The front lens simply functions as a cover. In such a multi-surface mirror, the size and angle arrangement of respective portions are determined so that respective portions reflect the light from the filament to a predetermined direction and a desired light distribution can be achieved by the integration of respective portions (refer to Japanese Patent Laying-Open Nos. 2002-50212 and 2002-50213).
By using such illumination apparatuses, a desired light distribution can be achieved efficiently.
It is to be noted that if the illumination apparatus, whether employed for a bicycle or carried as a general illumination apparatus while walking, allows light to be emitted from the circumferential side region, for example, in addition to the forward direction, visual confirmation by a vehicle, particularly by an automobile, approaching from the lateral direction, i.e. from the side, is facilitated in the dark. Thus, the safety of the carrier of the illumination apparatus can be improved.
In the case where light is to be output from a region other than the frontward region, another light source, different from the light source for the frontward direction such as a side circumferential light source was conventionally employed. However, use of another light source is not preferable from the standpoint of reducing the size, weight and energy, as well as the fabrication cost.